1. Field of the Invention
The present invention relates to a head-up display device capable of projecting a virtual image on a projection area of a windshield in a vehicle, and allowing the projected virtual image and a foreground of the vehicle to be superimposed and visually recognized through the windshield from an eye point of the vehicle.
2. Description of the Related Art
In recent years, with increased and diversified information required by a driver for driving a vehicle, head-up display devices (HUDs) that display a virtual image of information to be notified the driver of such as information high in the degree of urgency on a window shield of a vehicle, and allow the virtual image and a foreground of the vehicle in a superimposed manner have been employed for driver seats of the vehicles such as automobiles or trains.
As illustrated in FIG. 6, the head-up display device includes an indicator 1 for emitting a display light L, a casing 2 onto which the display light L is incident from the indicator 1, reflective plates 4 and 5 received in the casing 2 to reflect the display light L incident in the casing 2 and then guide it to an opening 3 provided in the casing 2, and a transparent plate 6 covering the opening 3 (see JP-A-2008-55940 and JP-A-2010-15037).